Here we refer the reader to the paper [1]} where a classical stopping time technique has been used for similar estimates in the case of systems.
(The idea of estimating an integral of a nontangential maximal via good-\(\lambda \)  inequalities and a Lipschitz graph determined by the stopping time goes back to
[2]}. New ideas were needed to make this approach work in the case of systems.)
In particular, Lemma 5.1, Lemma 5.2 and Corollary 5.3 of [1]} hold without any modifications for the system \(\vec{\eta }\)  considered here.
